Automatic switching



Se t. 192

p F. ALDENDORFF AUTOMATIC SWITCHING Filed Feb.14, 1922 9 Sheeta-Shaet 1 \Q aw a g a M h. mm M; MK I H #1 M oooouo mmw Db p 1927- F. ALDENDORFF 1111101111110 swl'rcnme Filed, Feb.14, 1922 9 sheets-Sheet 2 I 1,641,145 Sept 1927 F. ALDENDORFF AUTOMATIC SWITCHING Filed Feb. 14, 1952 9 Sheets-Sheet 5 Filed Feb. 14, 1922 9 Sheets-Sheet 5 hbi w mp

Sept. .6, 1921.

F. ALDENDORFF AUTOMATIC SWITCHING Filed Feb. 14, 1922 I 9 Sheets-Shut- 7 I12 vezz 502- IAldendozf Se t. 1927.

p F. ALDENDORFF AUTOMATIC SWITCHING 9 .Sfieets-Sheet 8 Filed Feb 14, 1922 I12 veniar: 1741616216101 Rum Mow ban Se t. 1927. 1,641,145

8 v Q? o Patented Sept. 6, 1927..

'jrjsrrz ennsunonir'sgos sn tnrtiwgnarsssnesr, GERMANY, Assam; or ONEH rovers ro een ro rsci-r, ornnw con-K, n.2,

AUTOMATIC.

swrrcrrane.

applicati'on 'fileclFebruaryT14, l922ySerial No. 536,504, and mferman -a rn 5, 1921.

."flh-i s-invention relates to l automatic switchingsyste'm's and moreparticularly to such systems as are employed for. interconnecting 'telephonelines. g

' Ac feature of the inyention is. that" the wanted lines are I first -,connected J by; Wanted line selectors composed of a group-of small switches whose. number .of bank contact pointsv is smaller :tlrairthe number of contact points in the banks of talking-connection andcalledeline-finders that are set on o-the selectedwanted lines by means ofthc said wanted. line-selectors; For example talking. connection called-lineefinders with contact banks. for 100 wantedlines may be steered I ontoaany'one of the 1G0 wanted lines by two small wanted, line selectors having only 1 0 bani: contacts or. contact sets each.

,The invention also mechanical telephone system in which the subscribers 'lines ai-edivided into groups of say. 100 lines'each and in which the talking connections are established by talking con nection switches'in the form of calli" connectors; wanteddine-connectors and trunk-connectors intermediate between the line and wantod-lineconnectors. all

v of which connectors are set onto the -pfl'oper line or. trunks by the aid of transitorily en-J gaged sw tches which revert to common use as soon as they have performed theirfuno tions; of setting the talkingconnection switches onto the proper subscribers linesand trunks.

The transitorily engaged switches coin: prise calling-line-finders, group-selectors wantedeline-selectors, and a-small mnnher ofsmall-auxiliary switches. l he number of transitorily engaged switches is proportionate tothe highest numberof diallin connection-establishing operations that occur at one and the same time,;and the-number of talkingeconnection switclf es .is proportional toqthe largest number of; simultaneousconversations. i x V ,The. invention also: relates toswitching devices which will act satisfactorily, under allrondi ions at service, asa line-finder, se This 0b3ect 1s accom,-'

lector connector. .jalished y constructing the switch in simh a manner that its; movable contacts move or jump i i-r one quick step straight into the ed line is reached.

relates to an electro- '-linegroup of bank contacts in which the line or trunk to which the connection is to be made, islocated,whereupon the movable contacts are moved at a slower speed until the want- Other features of the invention will appear in the specification and drawings.

The drawings show the circuits of a systeinfin which thetalking-connections are es-.

' tablished by talking-connection switches in the form of calling lineconnectors, wantedline-counectors, and trunk-connectors intermediate between the callingline and wanted-line-connectors,- and all of which connectors are-set onto the proper lines or trunks byth-e aid 01 transitorily engaged switches. A complete layout and diagram of the cir- Ctll s otthe novel system is obtained by put-- of 100 subscribers may be equipped with three groups of lOO-point talking connection switches comprising 10 calling line connectors C0 C0 etc. 1 0 trunkextendingswitches or trunk con nectors Ti TCQ, etc.

l0 wanted line connectors'VVc WC etc. and seven groups of small transitorily engaged switches comprising: i

(or more) calling line CFZetc. V

2 (or more) group selectors GS GS etc. 2 (or more) wanted line selectors S ii S etc. (Fig.9) V

(or more) pr'mary trunk finders PT etc. (Fig.1) I (or more) group selector finders GF tllietc. 7.) V

2 (or more) secondary trunk finders ST finders C1 ST etc. (Fig. 6)

etc. (Fig. 6).

in addition to these there-Inlay be a call ing line identifying device CJ, Figv 2, and a wanted line identifying device NJ.

To the pairs'osf switches ST, AF and ears air-f ore-ice. ]i

ting Figs. l9 together inthe manner in- 3T Al are assigned (in addition to their 4 functions of, connecting engaged wanted line 7 v .7 1 4 connectors lVS't-o secondary trunks 825 825 not etc.) the functions at identifying the proper :aaanulary trnnlo: to which the trunk connectors TC, is}, must connect in order to correctly establisl'i talking coiniections prepared by the transitorily engaged system. This will be hereinafter more fully described.

Each calling line connector CC, Fig. 1 has tour wipers and tour corresponding rows ot 100 haul; contacts each. The bank contacts oi each grtulp of calling line (-on uectors CC are connected in multiple and to T00 subscribers lines. One oi the bank contact rows of each calling line connector GU s cmmected in n'iultiple with the corresponding rows ot the other calling line conne tors and al o with a row of bank c ntacts in each oi" the calling line finders Cf oi the same group. 7

The trunk connectors Tc, Fig. 3, have five wipers each which are arranged to return to a definite normal position whenever they are released. The calling line ctn'mectors CC have no definite normal position. The bank contacts of the trunk connectors TC are divided into ten groups of ten contact sets each. At the beginning of each row of ten contact sets there is a preliminary contact which marks the group of contact sets into which the five wipers of the switch are to be moved. Associated with each trunk connector TC is an auxiliary selector GS which has one wiper only that is restored to a definite normal position. whenever the switch is released. The wiper of the auiiih iary or group marking switch is arranged to nialte contact with anyone of ten bank contacts. These latteare each connected to a correspomling prelin'iinary contact in the bank of the a sociated trunk connector TC. The contact sets of the banks of the trunk connectors T C of the ten dill'erent- 100 groups or the exchange are all connected in inultipie it being assumed that the system descr d herein is for 1,000 lines, although the same system could of course be used for larger exchanges.

Each called line connector C s provided with four wipers that are restored to their normal position when the switch is released. The contact bank of each of these switches has four rows of bank contacts. the contact bank being divided into ten groups of ten contact sets each. At the beginning of. each grou there is a preliminary group marking contact. The hank contacts of the called line connectors of one and the same 100 groups are all connected in multiple. The subscribers lines of each particular 100 group are associated with three bank contact rows oi each switch lVC of the corresponding 100 group and the fourth row of bank contact as well as the preliminary contacts are connected to the wanted line selec tors WS of the corresponding 100 group.

The calling line finders CF are each provided with a plurality of sets of wipers, there being a plurality of wipers that hunt simultaneously :tor calling lines. The contact bank for 100 lines may be divided into say 5 groups of 20 lines each and each one of live ditlerent wipers may hunt for a line in its particular group. By this means every one of 100 lines may he tested in 20 steps. Associated with each of the simultaneously hunting wipers of a calling line finder is a test relay T and for each group of test relays T there is a common relay S. In Fig. 2 each calling line finder is represented with three simultaneously hunting wipers and three corresponding testrelays T, T T Of these test relays only one can he energized at one and the same time because nleans are provided for preventing the energization of more than one test relay in case a plurality of simultaneously hunting arms strike upon calling lines at the same moment. When a test relay is energized a calling line is connected through to a free group selector GS. lVhen several calls are made in the same group at the same time each call is connected through to a difi'erent group selector GS. lVhenever a call is made all the calling line finders (ll? are started together. The order in which the calling lines are connected to the contact banks may be difl'erent in the dil'i'erent calling line linders so that each finder will test different lines when the finders operate simultaneously.

Each group selector GS has seven wipers wnich are restored to normal whenever the switch is released. The bank of each group selector has ten sets of seven contacts each. The first live contacts ol? each contact set, counting from the right. i connected to wires that lead to av certain wanted group. Thus the first five contacts oi the first set lead to the first 100 group, the first live contacts of the second set lead to the second 100 group and so on. These bank contacts of the group selectors GS are not connected in multiple. The sixth and seventh contact of each set are connected in multiple with the correspond ing contacts in the banks of the other group selectors in the exchange.

The wanted line selectors \VS have only two wipers each which are restored to normal when the switch is released. For each of the wipers of the wanted line selectors there is a single row of ten bank contacts and the corresponding rows of the contact banks of the wanted line selectors are connected in multiple. The multiples connected to the bottom rows of the banks of the switches \VS are connected to the inner row of each group of catch bank of the wanted line connectors and the multiples of the top rows of the banks of the wanted line selectors VVS are connected in multiple with the H in! preliminarycontacts at the beginning ofhave five ewipers each With corresponding rows o l hank contacts the nu1nher.o1"'-contacts in each row bein' e ual .to the number ofgsecondary talking trunks st witlrwhich the secondary trunk, finders ST cooperate. Thesecondary trunk finders ST 'have fno definite Znornial position;- Associated with each secondary-trunk finderySTis a dialling wipersand five corresponding rows ot-hanlr contacts. The number or contacts in each row is equal to the numherof dialling trunks orwanted line selectors NS. The dialling trunk finders 'ha'ye lie-definite normal position. r K 1 'i he identifying device 3J5 Fig. '2, has three Wipers and three;corresponding contact rows in its contact bank. The number of contacts in .eachrow is. equal to the number.

ofdia'lling trunksor group selectors GS.

The identifying device V J, Fig. 9,. is also provid d with three. Wipers. and the numher of bank contacts in eachv row is equal to, the number-pf dialling .;trunks or Wanted line selectors WVS.

7 devices has any definite norinal position.

All of the above-mentioned selectors or switches, and identifying devices are uniinotional and theircontact banks'inay-he'circ lar or straight as. in; switches at the panel typn 1 The group selector. finders GF-aie each, provided with a plurality of-s'ets'ot' wipers with iire Wipers .in each set. Each set of Wipers cooperates with ten different sets of bank contacts. The sets of corresponding groupsiof hank contacts. of the dilierent groupselector findersare connected in multiple "with each other. ."Thejcontact bank multiples of the group selector. finders GF lead to contact sets in the contact banks of the various igro'up selectorsGS in the ex: change.

nected' to the first set of contactsin the bank 0t each group selectorifinder-Git GFT, etc.

of the first group of. the exchange. The first five contactsof 'the second set of the.

bank of the; first group selector G53 'ofthe first group lead to the first set'of contacts; in .theloanl: of each: roup" selector finder. (similartoxGFi ',GE of the second -16!)v .fhleithen-ot the identifying he first gfi e contacts. (counting roin theright) otthe group selector GS of the first group oi' the exchange are congroupof the exchange. The first five contacts of the first set ofthe contact bank of the second group selector GS of the first 1.( )O; group lead to the firstiset of the second contactgroup; of each group selector finder V :etcof the first 100 group and;

set of contacts in the bank of the second Y the group selectojr GS leads to the, first contact set of the second. contact group. of the-bank o t each group selector finder (similar to GF ,'-GF ,;etc.) of the second group of the exchange and so on. The contact sets of the contact banks of the group so lectors GS, GS? etc. of .the second thirch.

fourth and other 100 groups of the exchange are connected in-a. corresponding nianner to the banks of the group selector finders of all the 100 groupsfli'n the exchange as Willhe more fullyexplained hereinafter With ref-j up afterthe'finders have executed only a few steps. In many cases the finders will not need to move at all. Means, are provided for prextentinga number otc-alls from being extended to one and the same diallingztrunir or anted lineselector VS simultaneously and for preventing one andthe saine call fromheingestended to two dilierentdialling trunks.

The wiring of the various switches; of a 100 group is substantially as follows:

lVi-res extend from the line relays ARand the auxiliary relays TR- associated with "1e subscribers lines' to theban r contacts of-the calling line connector-s CC andt-he Wanted lineconnectors act one a d the same 100 group.- The'relays associatedwith the subscribers lines hare; connections that lead to the'ca-lling line finders GFof the particular 100 group. These connections include firstly the Wires that lead to the operating Inagnets of the calling line finders CF, the test Wires that lead to the test contacts of the calling line finders'CF of the particular 100. group and dialling Wires through which dialling impulses aretransinitted from the line relay-s through the calling line finders GF to the group selector-GS and also to the trunk connectorsTQ; After a group selector Gshasbeen set-onto the set of contacts that leads to the wanted group dialling impulses are sent'hy means of the line relay through the group selector Gfi and through group selector finder G1? to a wanted line selector S, Fig. 9.. l

Each callingline. connector CC is con nected through primary trunk pt to a trunk conneotorTG and fFOlHfifiCliuOllhgct et. "Q y-th heukae11, trunk ca med-0. a

secondanv trunk at leads to a wanted line connector WU. The contact bank of each trunk connector is divided into ten groups and the ten contact sets of each group lead through ten secondary trunks to ten wanted line connectors ot a. corresponding 100 group.

In the calling line identifier CJ there is a separate bank contact (as 14:5) for each calling line finder of the particular 100 group and a separate bank contact (as 125) for each primary trunk finder PT. By these contacts battery is applied to only one bank contact of one calling line finder CF and to only one bank contact of one calling line connector CO at a time as will be hereinafter more fully described.

Starting wires for energizing the operat' ing magnets of the group selector finders GP lead from the banks of the group selectors GS, and stopping wires also lead from the banks of the group selectors GS to the banks ot the group selector finders.

Associated with each secondary trunk at is a separate identifying wire, as ti, tor each secondary trunk finder ST. These identitying wires are not multipled at the banks of the secondary trunk finder ST. By i'neans ot these identifying wires battery is connected to a bank contact of a trunk connector T C in such a way as to cause the connector to extend a. call only to the particular second ary trunk to which a call has been advanced to the said secondary trunk and also to the trunk connector TC that has been aitlected by the same call. This will be more fully described hereinafter. The identifying circuits for setting the trunk connectors TC onto the proper secondary trunl; extend from the secondary trunk finders S'l through the said identifying wires, through wipers of: the trunk connectors TC and tln'ough the primary trunk finders PT. the group selectors GS, the group selector find crs GP and the dialling trunk finders All and back to the secondary trunk finders ST as will be hereinafter more fully descril'ied.

The identifying device VJ applies battery to one bank contact in the bank of one wan ted line connector and to a wiper of one want cd line connector VG at a time. The identifying wires for doing this lead "from the bank of the identifier U to the wanted line selector and to the banks of the wanted line connectors on the one hand and through the dialling trunk finders AF and the secondary trunk finders ST 011 the other hand. as will be hereinafter more fully described. The identifier VJ applies battery to only one wanted line selector \VS and to only one secondary trunk finder ST at atime.

The operation involved in establishing a talking connection by means of the system illustrated will now be outlined.

hen the subscriber S makes a call by raising his receiver the line relay AR, Fig. 1, is energized and closes a circuit for the auxiliary relay TR which is a marginal relay and is only partly energized when the subscriber calls.

The auxiliary relay when partly energized causes all the disengaged calling line finders CF oi the group to which the calling subscriber belongs to be started and the calling line finder that first puts a set of its wipers onto the contacts corresponding to the calling line connects the dialling wires of this line through to a free group selector GS. The moment the dialling wires are thus connected through, the calling line finders that were set in motion are all stopped. It the wipers ot' a tree calling line finder CF should have happened to be standing on the contacts oi the calling line the latter will be connected through at once without the wipers of a. calling line finder having been set in motion. It several sets of wipers of one and the same calling line finder each strike upon a calling line or happen to be standing upon such lines a call will be connected through over one set of wipers only and the other calls will be prevented from being connected through over the other sets of wipers. To this end each finder CF has a separate test relay T tor each of its several sets of wipers and a relay S which is common to the relays T. The current lead to the energizing windings of the test relays T passes through a back contact of the common relay S and this lead is disconnected at the said back contact when a test relay together with the relay S is energized so that the current lead to the energizing windings of all the test relays is opened. Before this happens, however, the particular test; relay that was energized together with the common relay S forms a circuit for itself through a second winding by which it is maintained energized while opening the lead to the second windings of the other test relays. lVhen a test relay and the common relay in the finder are thus energized they cause their energizing current, which flows over a winding of the auxiliary relay TR. of the calling subscriber, to be increased in strength so that the marginal relay TB is now fully energized.

The calling subscriber S now sends in his hundreds selecting impulses and these are translated by the relays AR, TR to the rotary magnet or operating magnet HM oi the group selector GS that has been taken into use. The wipers of this group selector are thus set onto the particular set of bank contacts that leads to the desired 100 group in the exchange. These 100 selecting impulses, however, are also sent through the operating magnet Do in a trunk connector T0 and cause the wiper of a group marking switch GS in the trunk connector to be set onto a contact by which the corresponding group of Ill) contactsin the bank of the trunk connector; TC- is marked. The group selector GS of the dialling trunk is connected before the dialling impulses are sent in by a primary ,trunk finder PT to a free trunk connector s I I 7' V Letit be assumed that the calling line S Fig. 1, is now connected through the calling line finder CFflFig. 2,to" the group selector GS}, Fig. 4", and through the primary trunk finder PT Fig. 1, to'the calling line con-- nec'tor (3G Fig.5 1, and to the trunk connec tor T6 Fig; It will also ho assumed that the group in'arlringswitch GS of TC Fig. 3, and the group selector (Er-S Fig. 4, have been set by the hundreds dialling impulses onto their first contact or set of bank contacts,'that is to say the calling subscriber desires to establisha connection with a sub- 1 'scriiber in-the'lOO group to which he himself belongs. I I r Thefirst hundreds impulse gives rise to an impulse that flows-through a slow actin'g relay V Fig. 2, and throughcthe operatlng r mag-DetsHh P and Dg jot G Fig-yet, and 'GS F 3, respectively. The} slow acting relay'v lre'eps its armature-attracted until thehundreds impulses haveall-been sent in and in so doingcauses thecalling lineidentifier GJ, Fig-2,- to set its Wipers onto the dialling trunk used-by the calling subscriber. Thefsaid slow acting relay V closes the circuit otthe operating magnet Dc of the identifier CJ whose wipers are thus set in" motion. As soon as the-contacts corresponding 'to the dial-lingtrunlr.used a're -reached arelay J associated with thistrunk isene'rgized together with the test: relay To in the identifier." The testrel ay opensfth'ecircuit of the rotary magnet D0 and thus stops the brushes of the identifier and the relay J closes energizing circuits which extend: through the primary trunk finder- PT "to a relay F in the calling line connector thu's energizing the-relayF which closes-the circuit of the operating magnet T0 of the calling line connector CC Fig.- 1. The 'Wi-pers'o'f (3C are-thus set in motion; When the identifier CJ" is stopped on the dialling trunk used an identifying circuitwhich' is individual to the dialling trunlrused and eX-' tendsthrough the primary trunli' find'er PT and through-therelay' Pc '0f the connector CO is" prepared and this identifyingcircuit is closed as soon'a s the ipers of CO strike "the contacts that are connected throughthe caning line finder used for the connection to tliefpiirti cul'ar diallingtrunlr to which the calling subscriber was previously"connected. The said identifying circuit then energizes f the-ideutitying relay P0"? which opens the circuit of the rota rymagnet"D0 ofthoconnector' Q0 A relay P 2', in the calling] line finder CF is energized together with the {is-identifyingrelay P0 and opens the circuit U in the'gro'upselector GS and this relay of the relay J The operation of setting the calling line connector (1C onto the prop-er line is independent of the dialling operations,-.i. e. ofrthe 100 selecting impulses of the call ingvsubscriberand may be completed; before or after the hundreds impulses have'been' sent in. Hence, the calling line connector will be abletotravel if necessary over its 100: sets of contacts before it is affectedby.switchingoperations that occur in the dialling trunk with whichit is temporarily associated; V i o The slow acting relay V that is energized at the commencement of the hundreds impulses also closesthe circuitof another slow acting relay WV? which prepares a circuit for a relay [Pin the group selector G8 VVhen'the hundreds selectingimpulseshave all been sent in and: thegroup selectorGrS has'been set onto the set of contactscorresponding to the wanted group (the first group in this instance) and when the-slow acting relay V has had time to fall back, acircuit isclos'ed for the. operating magnets D of all thegroup selector finders Gr-F that=liappened-to be'idle at that moment in the desired group. As each of these group selector finders has a pluality of simultaneously hunting wipers, the

operation oi connecting the-calling dialling. trunk through to a wantedline selector will only require a i ewastepsto be carried out by the group selector finders. Hence, the calling subscriber will always be rapidly con nected through toa wantedline selector "VVS and there will'b'e 'no' danger of tensselecting impulses sent in by the call-ing subscriber being lost. As soon: as a set of wipers of one of the group selector finders 'GF, say GrF has reached.the calling 'dialling trunk, a test relay,-say-Tl in GF is energized and opens the circuit of the operating magnet D ot-the finder GF so that this finder is stopped. In order to preventseveral calls from being connected through to the same wanted line selector in case several sets of brushes of a finder lend upon several callin lines at the sameinoinentia separate test relay T is-provid'ed for eachset of brushes and the lead to the; energizing 'windings of these relays passesthrouglrthe bank contact of a relay S which is common to all the inrl'ivi'dfial test relays and which is opened the moment-an individualtestrelay isenergized'. The pan ticu'lar individual test relay energized esh tablishesa new ci-rcu it through an auxiliary winding, but the. currentleads to all the othertest relays are out off. Thus only one calling dialling trunk-is connected through anyone finder and the other-calls are'eX- tended througli other finders GF.

f The energizing circuit o-f t'he particular test relay, say T operatedinthelgroup select'onfinder GF extends through the relay U opens the energizin'g circu-it of the op- Lil ltl

crating magnets of the group Selecting tindera til at the selected group.

The eallint subscriber now sends in his tone dialling impulses which are. t 'anslated by the rein AR Fig. 1, into the operating niagnet ZM ot the tens designating switch of the wanted line selector S to which the call has been extended. The operating; magnet ZM steps its wiper t onto the tens designating contach say the first tena designat ine' contact: 3&9, Fig. 9.

The energizing circuit oi the operating magnet Z31 extends through a slow acting relay VIZ which closes the circuit of a relay 5T when its armature drops back. The relay 5T then cuts out the tens operating magnet ZM and includes the unite operating magnet Elli in the dialling circuit controlled by the impulse relay JR 'lTh-e slow acting relay V that is: energized when the tens dialling impulses coi'nlnence coming in also causes the wanted line identitier U to set its brushes onto the dialling trunlt used for the connection. The operations involved in this function are similar to those described in connection with the calling line identifier Cd, Fig. 2.

The relay S ot the group selector finder til which was eiiereized when this tinder extended the call will now hare caused an idle auxiliary tinder AF, say it, Fin. (5, to have set its wipers onto the dialling trunk need for the call, i. e. the dialling: trunk correspoiulino to the finder (Hi and the wanted line Selector ll tii The particular secondary trunk finder ST that is associated with the auxiliary tinder AF need for the call will have preselected a secondary trunle say the trunk az that terminates in a wanted line connector C As soon as a pair oil switches. say Al ST has connected an idle wanted line connector \Vt to the dialling trunk (TF W3 used for the cell a relay 0 associated with this dialling truni: energized and it then closes the starting circuit oi. the trunk connector TC previously seized tor the call. This Fdilllllllg circuit tor the trunk connector T0 Fig. 3, extends from the relay Fin. 7. through the grroup selector tinder G F and the n'roup selector (i95 used for the *all and through the primary trunk tinder PT to the operatinn niagrnet D that moves the hrushea oi? the trunk connector T C The brushes of T0 are now moved until they reach the particular secondary trunk which has been con nected through a pair (it switches 8T All to the dialling trunk GF ST used for the call. The function of stopping; the wipers oi. the trunk connector TC on the proper secondary trunk at: is performed by identit'ying' circuits ti H which are connected to the banks of the secondary trunks CT that are not niultipled thereat. Each secondary trunk has a separate identifying wire leadinp; to a contact in the hank of each switch cl'l. l-icnee, it there are two secondary trunk linders iilil, ST the secondary trunk 861 will have one idcntiith 'iug wire ti" leading to a contact in the hank oi the switclh t li and one wire ti lmding to a contact; in the bani; of the nvitch JT The other see ondarv trunlqa an at also each have a sepa rate wire connected to separate contacts in the hanks-s of the switches ST ST The ltltlliiji yil'ltl wires that emanate from the bank of the secondary trunk tinder JT are each coniiected to one oi. the contacts oi. the tirst vertical row of contacts of each of the trunk connectors TC and the identifying wires that emanate from the bank of the sccoi'idarr trunk connector ST are each conllcta'ttl to a contact in the second vertical row of each of the trunlc coin'iectors TC. Hence. it a potential is applied through an identityingr wire that emanates in a second ary trunk tinder S'l. one contactin. the tirst vertical row of contacts in each trunk connector TC will be coi'inectml to battery and it a potential applied through an identifying; wire emanating jt'ronl the sec ondany trunk tinder 3T battery will be connected to one contact in the accond vertical row oi. contacts in each trunk connector TV. It will now be evident that it arrangements are made by which only the first brush or wiper can he connected to the other pole oi the battery when the opposite pole lllh heen applied. througrh the secondary trunk finder ST" to a contact in the first vertical row of the haul; the particulajtrunk cmineetor will only he stopped by the identitying circuit when its wipers reach the particular secondary trunk onto which the wipers of the secondary trunk tinder t lT have heen set. And Further it the arrangements are such that the wiper ot a trunk connector TC that travels over ite second vet-tie: l. row of contacts can only' be conncct'cd to the other pole of the battery when the opposite pole has heen applied through the secondary trunk lilidcr S'l to a contact in the said second vertical row the identifiainp; circuit of the trunk connector an only be closed when its brushes strike the set oi contacts connected to the particular secondary trunk onto which the seemidary trunlctinder ST ha been set. The ident-i tying circuit includes a relay (371 (Fig. 3) in the trunk connector and this identifying relay (5T1 opens the circuit of the operating;- magnet T) when the. trunk connector has its wipers onto the pro jiei' secondary trunk.

While the trunk connector is thus extend: ingr the talking: circuit to'a wanted line connector WQ Fig. 8 the settingof the wanted line selector lVS, Fin. 9, used for the connection proceeds. On the calling: aubscriber ti Fig. 1. sending: in hia units dialling ilnpulses, these in'ipulses are translated by the ltlt) i ar-i; T4 5 proper tens" contact and" by the'units desig nating Wiper a When the first units dialling impulse-is sent; in a circuit islclosed at an oif-norinal contact 706 3581'61 the operating r'na gnet D6 of the wanted'lineconnector. This circuit extends through the pair of switches AF ST that hasconnected the dialling trunk to the seeondary talking trunk 86 The wanted line connector VVC is thus set in motion before the unit inn"- p'ulse's have all beensent in.

' he wantedhne connector VVC s. now

set of contacts-or wanted subscribers. line th at has been designated by the designating wipers and u}. 7 a

If the W'a'nted line is busy by having made a call or by its having been called by another subscriber the test relay in the Wanted line connector set-onto the contacts or the wantedline- S will not be energized and therefore a busy signal-eircuit-will'be closed when a slow acting relay V (Fig. 8),"enerize'd in the circuit of the operating inagnet De o-f the Wanted line connector, allows its armature to drop back; The said busy signal circuit includes a busy relay- BB ,Which applies'a bi'isytone from abusy current generator BSu' to one limb of the talking circuit which extends back through the trunk connector'TC and calling*line 'c0nnector CC to the calling subscriberf S When thes'low acting relay V of a wanted line connector WC drops back as described the release magnet ME of the Wanted line connector is energizedand ,rest'o'res the connector to its normal position. On'th'e calls in'g subscriber replacing his receiver. a relay Tc in the calling line connector 0C is deenergized and its arniat'u're closes an en-' engizing circu t for the restoring'i'nagn-et M ofthe trunk connector"TC which restores the wipers of this switchto their normal po- "sition. The Wipers of the calling line connector 06 remain uponbank contacts on which they are set. V l i v e The release of the switches associated with the dialling trunk is efl'cted independently of whether the Wantedsubscriber is busy or not by ne'ans of a'relay 645, Fig. 9 in the Wanted lineselector'VVS the monient the wantedline connector VVC has'been set onto thefcontactsofthe'wantedline. The said relay 6 causesth'e wanted line selector to'b erest'ored to its norrnal position and simultaneously makes the wanted lineiden-' tifierVVJ available for another call. It also j' releases the group vSelector finder'GrF loy calling subscriber;

The'relay P6 on energizing connects the causing" the circuitof the relay S of this finder to' be opened. The deenergizat ion of the relays is accompanied by the deenergization of the particulartest relay, as T ofthe finder GF and of the relay U of the group selector GS thel'atter being restored to its normal position by its release magnet M while the brushes of the finder GF re main in a position that they occupy atthat 'inoni'ent. The relay U in the group selector that causes this selector to be restored when its ari'nature tallsback alsojope'nsthe circu it of the relays S and T or the calling line fiIider'ClF and thus makes this finder made available fora new call as soon as a 'c'a lling line' connector, as C was set onto v V the calllng line. caused to set its wipers onto't-he particular t v p 7 When this happened a relay P0 in the calling line connector and also are-lay P intheca llin line finder CF were energized and the latter open the circuit of the relay J of the calling line finder "WC are set onto] its contacts the test relay P61" in the connector 6 isenergized and lockedfii'i the energized position. The locking-circuit of therelay P61 and also the energizin'g circuits of the'talking circnit-extending relay HR in the trunk connector TC and: otthe relay TeFin' the wanted line con- Hector V CFare'COntrOlled by the relay T0 in the calling line; connector CG and the c'ircuitot the relay T0 is controlled'by the ringinggenerator HQ to the talking circuit that extends to the wanted: station S and ringing currentsare'then projected periodically through the condenser G0 and the tiniingsWitchSS which closes the ringing cirafter the relay Pea of the connector W0 has been energized the circuits of release magnet Me and the busy relay BB of lVC are not closed but a relayFR Fig.'8,.'is energized'which causes a free signal generator FSu to be connectedv to the talking circuit-so that the calling subscriber receives a si nal which indicates that thewantedsubscri eris free. 7 I

" livhenithe wanted subscriber raises his receiver a "relay 656 in the wanted line connector 6? whose high resistance winding is connected to one linib of the talking circuit isenergized. This relay 656 is adapted to attract its armature. quicker than the line relay AR Fig. 8; associated with the wanted subscribers line. Therelaytee i'n1 "niediatelycloses' the circuit "of a relay 658 i wi l tacts in the banks'of the group selector G3 ,from the positive pole to the battery through of the second 100 group l'l is' connected by a bundle of Wires 1Qtotl1e twelfth set of'con-' tactsin each'of s stem -er the group se- 'lector finders in the, second 100 group and V the third. set otcon'tactsin the bank or the group selector GS? er; the second 100 group in an analogous manner.

is connected to thetWelt-th set'offcont-acts" in each or the banks of the group selector Thesystein:illustratedin the drawing also eludes ar angements i which calling subscrihers receive a signal in case all the inatcs togthe calling subscriber that he'sh'ould busy signal ceases relays T and Sin this finderwillfbefdeenere sv sitchc's in the the talk- 1 ing trunks areengagied. c,l?h1 :1s 1gnal intinot send anyilialling" ii npulses before the:

' cl until switches are available torhi'sca The circuits by which this signal is given Will hereina t'ter more hilly e cri ed; i

The novel Systenialso provides means by I which all the dialling circuits are immediately releasedufh en a calling suhscriqer aha ndons his calh only a callingline fiuderf CF should happen to. have been engaged the gizecl and thissuffices to restore or release the finderCF. It in addition to aca-lling line find 'CF t emu] ele r G o n thereto has also been partly or completely set the moment thecall is abandoned therelay S of the calling finder CF which dcenergizes when the calling subscriber re places his receiveralso effects the release of any other seized sWitchesCJ', GS,'P'1,'CC, TC. The relay S of the calling line finder Ch will, in such cases, also cause. the release of any other switches that haveibeen taken into, use, such as AF and andVZC. If the tens dialling impulses should have been sent in at the moment the callingsul'sscriher abandons the call thedeenergi zlation Oft e re] S oif the finder CF will also cause the anted line identifier U tohe rcstorechand it the units impulses should have Commenced coming in the iyanted line connector Will also he restored. 1 r Y The circuits and operations involvedin e tablishing a talking connection between two subscribers will now, be described in detail.

Vhen the calling subscriber S raises his receiver the line relay energized by a current flowing otter the calling line. The relay- AR closes at its Q itacts2 a circuit which extends froin the positive pole to a Wi d n f t e eui ia yr eyTR 9 tacts 2,41, resistance to to the 'negative p oleh The, r'=a1'ginal relay is partly energized to waist fie d est bl sh a ire U1 to the "negative pole.

contactsfit, wire s'l, Sdwhicli is common to the calling suhscrlhers group and thenis paralleltln ough Wires 9,11; operating mag- Df D7 contacts 1 0, 12, interrupter V The operating magnets of the idle calling linefindersCE "CF are thus alheiiergiZe'clQ The sets of {13ers or the calling (line finders are thus caused to travel simultaneously over (liii'erent groups of bank contacts; As soon as one of the Wipers connected to atest relay T T or T say, the Wiper 19 of a calling line finder CF strikes the contact, as 18 connected tothe Wire 16 0t thecalling line a circuit is closed which extends fronithe positive pole through the winding 18 of the auxiliary relay, 14, contact l5 of the energized line relay ARtwires 16 17,-Fig. 2, bank contact 18 of the calling line, finder'iQFfi Wiper 19, ire

20, low'resistance Winding 21 of the testrelay T back contact 22 ofthis relay, high resistance winding 23 of the test relay 1 Wire 2 h contact 25, l 1"igh resistance Winding 26 andlowresista nce inding 27 of a conmon relay S wires 28, 295 30, oil-normal contact [a ct thegroup. selector G'S h 2 tive pine.- The ay T1 n S1 in this cuit are energiz'ed. The foriner"short circuitsi ts high resistancejwinding by means of its contactli lfand-thus applies a busy potenitial tothe Wire 16 onto which the WlPCE'lQ has been'set. The relay also opens its contact 682 and thusjc utsofi' the battery from the energizing inding of the other test relays T and ofthe same calling line finder CF. The relay SP'by means of its contact 1550 short-circuits its high resistance inding 26' and at its contact 5 it opens the common 'batterylead to'-the-relays"T 1, T and T When the relay S is energized it also opens the circuit of operating magnet DF at 10 so as tostop the movement of the Wipers of (JFK The relay S also closes its contacts 544,201, 154; and opens a contact 580 for reasons which Willbe hereinafter described.

When the relay T shortcircuits its high resistance- Winding the current flowing through the winding 13 of the auxiliary relay TR is increased 'sufficiently'to cause the auxiliary relay'to be completely energized. It then opens its contacts 1 and 5 and closes its contacts 32 and 33. By the opening of contact 5 the circuit extending from the positive pole through. 7 8 to the various driving magnets ot the calling line finders is" opened so that'all theother finders hesides CF are stopped. By the contact the negative pole of the battery is connected to a Wire 34 and also to the winding act "the" auxiliary relay TR which latter'noW keeps the relay TR fully energized. here the "relay T in the calling line tinder was energized it alsoclosed the contacts lifi and 142. The flormer connected the stepping magnet Hhl ot the group selector GS Fig. 4:. to the dialling wire leading to the relay AR oi the calling subscriber and the contact l lZ prepared an identifying circuit that includes the identifying relay P Fig. 2.

The calling subscriber 55 now sends in his 100 dialling impulses which are translated to the stopping magnet HM ot the group selector GS so that the wipers ot the group selector are stepped onto the set of bank contacts that lead to the wanted 100 group which in this use will be assumed to be. the group of the calling subscriber.

" At each 100 dialling impulse sent in by the.

ailing subscriber S the armaturer's ot the relay AR drop back to close a contact 3'? and open a contact 1:3. The current tlowing through the Willtlll'lgS of the auxiliary relay TR will thus be intermittently intcrrupted. but as the relay TB is slow-acting it will keep its {Ilfll'lfltttlGS pulled up.

hen the contact 37 is closed as described by the first 100 dialling impulse a circuit 1 is completed which extends :t'rom the otttill normal contact 7t: 31, Fig. l wires 30. E29, 28, Fig. 2, winding 27, contact. 150 of relay S contact 631, winding 21 of relay T wire 20, wiper 19, bank contact 18 ot' the :alling line tinder CF wires 17, 16, Fig. 1, 3'? of relay AR, wire 38, Fig. 2, wire 39, bank contact 40, wiper all, wire 12, contact 43 of relay T wires eta, 45, Fig. t, contact 4:6 of relay U in the group selector G8 vires 47, =t8, Fig. 2 energizing winding 49 of the slo '-acting relay V wire 50 and then partly through the wire 51, Fig. at, to the stepping magnet HM oi the group selector and to the positive pole of the battery, and partly through the wires 52, 53, Fig. 1, wiper ht that will be assumed to have been set:

onto the primary trunk P'I, wires 56, 57, 58, Fig. 3. stepping magnet D of the group marking switch GS in the trunk connector T0 to the positive pole of the battery. It is thus seen that the 100 dialling impulses cause the wipers ot the group selector G8 in a diallingtrunk and the wiper ot a group marking switch GS associatietil with a talking trunk connector TC to be set simultaneously. the wipers of the group selector G being set onto a set of bank contacts that lead to group selector tinders G1? in the wanted group. and the wiper of the group marking switch GS being set. onto a contact which marks a group of bank con tacts in the bank of the trunk connector TCK The relays '1 and S are slow-acting like the relay TR so that they keep their armatures attracted during the intcrrup tions between the dialling impulse. The tirst 100 dialling impulses sent in causes the slow-acting relay V to be energized and this relay keeps its armature attracted until shortly after all the 100 dialling impulses have been sentin. It keeps the dialling in1- pulse circuit closed at its contact ()0 so that when the oft-normal contact is 31, Fig. at, is opened at the first step executed by the group selector G5 the dialling circuit is maintained closed.

Let it be assumed that the number of 100 dialling impulses sent in is Z so that the wipers of the group selector (i51 and the wiper of the group marking switcli G5 are each caused to execute one step.

\Vhen the relay V is energized it closes a circuit at its contact (.11 which extends from the positive pole of the battery through a contact 62 ot a relay J second winding (52} ot the relay V wires 64, 65, contact 66, stepping magnet: D0 of the calling line identifier Cd, interrupter the to the negative pole oi. the battery. The stepping magnet D0 and the windin 63 of the Sltiffltctlng rela i V are thus energized and the n'iagnet Dc steps the wipers o't Cj round until they strike upon the particular dialling trunk to which the calling line tinder ClF belongs. The winding 63 of the relay V will maintain the circuit of the stepping magnet Dc closed even it the 100 dialling impulses should cease before the calling line identifier (ll has been set onto the dialling trunk used. The winding 49 of the slow-acting relay V thus only serves to indicate the closure of the circuit of D0 when the 100 impulses commence coming in.

\Vhen the wiper of the calling line identifier strikes a bank contact that leads to the dialling trunk used for the call a circuit is closed which extends from the positive pole. of the battery through contacts 6]. and 62. wire 67, relay J wire GS, bank contact (39, wiper TO, relay T0 to the negative pole oi the lmttery. The relays 1 and To in this circuit are energized. the latter opening the circuit of the driving magnet Do at its contacts 66 and. thus stopping the wipers ol': the calling line identifier and the relay J closing a part which leads from the posit ivo pole of the battery through 7t. 72. 73. Fig. l. wiper T8 of the primary trunk tinder PT bank contact 70. wires 80, S1, bank contact 82 ot the primary trunk tinder PT. It the wipers ot' the primary trunk tinder PT should be standing on the set; ol bank contacts to which 82 belongs. or in other words. it the primary trunk finder PT should have been set onto the same lHlll'lttl) trunk a; PT the current path just traced would extend through the wiper 83. relay E11 ot PT, wire Set, Fig. 2. wires 85, 86 87. 88. Fig. 4, off-norn'ial contact Z1 89 which is closed as long as the group selector GS is in its normal })()Sltl01l,t0 the negative pole. The relay E77 is thus energized and at; its contact 90 it closes the circuit of the driving magnet Up on the primary trunk finder PC? This circuit extends from the negative pole of the lit) ease-145 battery to the interrupter contact 91 of the relay Sp, Fig. 2, wires92, 93,94,;Dp contact 90,.wire 95, Fig, 2, wires 96' 97, contact 98 of the relay J2 to the positive-pole. The'driving magnet D29 isthuscaused to n1ovethe wipers ot" the trunk finder P -F away from the bank contact-s otlthe-trunk seizedby the trunk finder PT a-ndlthe movement of the wipers PT continues until they reachadisengaged trunk, i, e. a trunk whose contact that corresponds to 424 ofHR -,Fijg. 3, in the trunk connectorTC in whichit terminates is not closed.

The closure of the contact 71 of the relay J 1 also results in the completionotthe following circuitz'Positive pole or thejbattery 71, Fig. 2, 72, 73, wiper 78 bank contact wires 80, 99, 100, Fig.3. contact 101 of relay H11 in the trunkconncctor TC wires 102, 103, 104; relay'F to the negative'pole. The

relay F is energized and preparesa circuit for the relay Pc at tl'ie contact'129f At its contact 11.8 the relay F a'ls'oclo'sejs. the

circuit of thedriving magnet- Dc? oft-he calling line connector CC. which extends from the positive pole through 118,119,120,

121, D0 U6 to the negative pole. The

driving magnet now: causes the wiptrs' of the calling line connector tobe'step'pjecl' onto the set of bank contacts that" leads to the particular calling subscriber lS w'hoSe call was extendedflthrough th ecall'ing'l'ino finder CF and through the primary trunk finderPT to the primary trunkPt to: which contact 142. wire 148 Relay P Fig; 2, bank I contact 145 wiper 146 of thecall'ing line iden-tifierCJ to the negative pole.- The re-" lays P, Fig. 2 and F0 of the callingfline connector CC, Fig.1, are energizedi' The latter relay opens at its contact 121 the e-ircuit o-t thedriving magnetDc and stops the wipers of CC on the calling line. its contact 148 the relay P0 closes-an energizing circuit for th-e'relay Tc 'whi-ch eX tends from the positive polethrough thecontact 148 relay T0 wiper 1429 bank contacts 86 of CC, wires-35. 34. cont-acts '32, of

the auxiliary relay TR toithe negativepole.

The relay T0 on energizing closes a locking circuit for itself which extends. through 454 and keeps itself energized independently of the contact-148 P0 and also maintains the circuit of the driving magnet- Dc op-en after the relay Pc is deenergized anclcloses contacti12'1. At its contacts 318 the re lay'lc also connects the positive pole to the wire 317' by which operations are started that will be d'escrihedlater. o The relay P Fig. 2. that is energized: at

the same tiine as P0 opens at its contact 152 i the locking circuit that the relay J had closed for itself and that extends through 151,152, 153, 154 to the positive pole. The

line identifier CJ are thus simultaneously deenergiz-ed and the identifier CJ then immediately becomes available for other calls.

The slow acting relay V which was energized together with the stepping magnet of the group selector Gs Fig. 4, and

relay J and also the relay To in the calling "J thestepping magnet D9 of the roup narking switch G8 Fig. 3 closes the circuit of a slow acting relay VV inthe group selector drops back after the relay WV? has been energized a circuit 18 closed that extends from the positive pole of the battery through relayWV wires 157, 156, contact 1590f the deenergizeclrelay V wire 160, contact 161 of the relay VW, contact 162 of the relay U Then the armature of the relay V wire 163, wiper 164, bank contact1'6-5 of the roup selector G3 wires166', 167, 168, Fig.

partly through 171, 172, drivingmagnet D or the-group selector finder GF contact 173, interrupter U?) to the negative pole. The two driving magnets D and Dand the relay thus receive current impulses by which the wipers of the group selector finders GF and GF are caused to travel over their bank contacts until a' hunting wiper strikes the dialling trunk onto which the group selector G8 has been set. The said impulses also keep the slow-acting relay WV energized, 'lVlien a hunting wiper ota group selector finder, say GE reaches thendialling trunk onto 'which the group selector GS h21s been set a circuit is comp-leted which extends from the positive pole of the'battery, relay V Fig. 4, wires 157, 156,"Fig. 2, contact 159' of relay V wire 160, contact 174 of W Wire 175, relay, U wire 176, wiper 177, bank contact 178,wires 17 9', 180, Fig. 7, bank contact 181, wire 188, low resistance winding 184, contact 185, high resistance winding 186 of the relay T of the group selector finder GE, wire 187, con tact 188, high resistance winding 189 and low resistance winding 190 of the relay S, wire-s 191, 192, Fig. 9, 198, contact 194 of the release magnet M of the wanted line selector or designating switch W'S tothe negative 3 pole of the battery. The current flowing in this circuit energizes the relays U of the group selector G8 and T and S of the group selector'fincler GF The relay U at its contact 46 disconnects the driving mag- I andjthen partly through wire 169, stepping magnet D of the group selecting finder 'GFK, contact 170' tothe negative pole, and 

